voonhous commented on code in PR #19809:
URL: https://github.com/apache/hudi/pull/19809#discussion_r3916152801
##########
hudi-common/src/main/java/org/apache/hudi/common/schema/HoodieSchemaTypePromotion.java:
##########
@@ -19,20 +19,28 @@
package org.apache.hudi.common.schema;
/**
- * Defines type promotion rules for HoodieSchema compatibility checking.
+ * The single table of primitive widening promotions, used by {@link
HoodieSchemaProjectionChecker}.
*
- * <p>Type promotion allows a reader schema with a "wider" type to read data
- * written with a "narrower" type. This follows Avro's type promotion
rules.</p>
- *
- * <p>Supported promotions:
+ * <p>A promotion lets a reader schema with a wider type read data written
with a narrower one:</p>
* <ul>
- * <li>INT → LONG, FLOAT, DOUBLE</li>
- * <li>LONG → FLOAT, DOUBLE</li>
- * <li>FLOAT → DOUBLE</li>
- * <li>STRING ↔ BYTES (bidirectional)</li>
- * <li>Decimal precision widening: (p2-s2) ≥ (p1-s1) and s2 ≥ s1</li>
+ * <li>INT -> LONG, FLOAT, DOUBLE</li>
+ * <li>LONG -> FLOAT, DOUBLE</li>
+ * <li>FLOAT -> DOUBLE</li>
+ * <li>STRING <-> BYTES (bidirectional)</li>
+ * <li>STRING <- any numeric type</li>
+ * <li>decimal widening, see {@link #isDecimalWidening(HoodieSchema,
HoodieSchema)}</li>
* </ul>
- * </p>
+ *
+ * <p>Logical-type-over-primitive promotions are deliberately NOT in this
table. A TIMESTAMP reader over a
+ * LONG writer, or a UUID reader over a STRING writer, is accepted by
+ * {@link HoodieSchemaCompatibilityChecker} for reader/writer compatibility,
but it must not make a bare
+ * long a "compatible projection" of a timestamp: writer-schema deduction
would then silently drop the
+ * logical type. Compatibility and projection are different questions, so they
use different tables.</p>
+ *
+ * <p>One more difference is documented rather than resolved:
+ * {@link #isDecimalWidening(HoodieSchema, HoodieSchema)} additionally
requires the same backing (fixed
+ * versus bytes) and, for fixed, an equal fixed size, whereas the decimal
check in
+ * {@code HoodieSchemaCompatibilityChecker} compares only precision and
scale.</p>
*
* <p>This class is package-private and used internally by schema
compatibility checkers.</p>
Review Comment:
Done in d74b3cd4f3b6.
##########
hudi-common/src/main/java/org/apache/hudi/common/avro/AvroSchemaUtils.java:
##########
@@ -39,7 +39,14 @@
import static org.apache.hudi.common.util.ValidationUtils.checkState;
/**
- * Utils for Avro Schema.
+ * Avro-typed schema helpers, retained only as the delegate target of the call
sites that have not moved to
+ * HoodieSchema yet: {@link
org.apache.hudi.common.schema.HoodieSchemaUtils#asNullable(HoodieSchema)} and
+ * {@code HoodieSchemaUtils#createNullableSchema}, the field construction
inside {@link HoodieSchema.Blob},
+ * and a handful of internal uses in {@link HoodieAvroUtils}.
+ *
+ * <p>This class is being retired under #16639. Do not add methods here: the
HoodieSchema twin of every
+ * method on this class already exists, so use {@link
org.apache.hudi.common.schema.HoodieSchema} or
+ * {@link org.apache.hudi.common.schema.HoodieSchemaUtils} instead.</p>
Review Comment:
Done in d74b3cd4f3b6.
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